Numerical simulation of flat-nose projectile penetrating concrete and soil target

Transcription

1 3rd WSAS International Conference on APPLID and THORTICAL MCHANICS, Spain, December 14-16, 27 9 Numerical imulation of flat-noe projectile penetrating concrete and oil target DONG YONGXIANG, FNG SHUNSHAN (State Key Laboratory of xploion Science and Technology, Beijing Intitute of Technology, Beijing 181, China;) (mail: dongyongx@bit.edu.cn) Abtract: The penetration into target compoed of concrete layer and emi-infinite foundation oil with flat-noe projectile i imulated with three-dimenional LS-Dyna finite element oftware. The deformation proce and failure zone in the target are decribed. The penetration performance of projectile with flat noe i dicued. The penetration depth, the reidual velocity and the deceleration amplitude of projectile increae with the initial velocity of projectile. And the penetrating crack and the tenile cruh zone indicate the damage of the target. The phenomena of concrete damage are in agreement with the experimental reult. Key-Word: numerical imulation; flat-noe projectile; penetration performance; target 1 Introduction Kinetic energy penetration i of importance in military application (terminal ballitic). A lot of work about Kinetic energy penetration into concrete target ha been done and pleaing achievement have been obtained [1-3]. Literature [4-6] carried out on the penetration mechanim on concrete and literature [7-9] conducted numerical tudy of penetrating concrete target. The projectile noe hape on the penetration ha an important effect on the penetration characteritic. The penetration of the flat-noe projectile, a a blunt projectile into target i an intereting work to do. Although plenty of work about the penetration into concrete target, but the work on the penetration into target compoed of concrete layer and emi-infinite foundation oil with flat-noe projectile i neceary. Thi paper tudie the penetration characteritic of the flat-noe projectile into concrete layer and emi-infinite foundation oil with low velocity. 2 Problem decription Impact of projectile into target involve in many factor, uch a the initial velocity of projectile, ma of projectile, geometry of projectile (epecially the noe of projectile), angle of attack and material of the projectile, geometry and material of target. Lot of experimental reult on the penetration into concrete target how that during the proce of the penetration of the projectile into concrete target, the urface of target adjacent to the poition of impact will occur palling becaue of the free urface effect of target and hear and extruion effect formed by projectile penetration into target. The tudy problem by numerical imulation in thi paper i the normal penetration of the flat-noe projectile into concrete layer and emi-infinite foundation oil. The flat-noe projectile i 69 mm in diameter and 151 mm in length. The flat-noe projectile i made by 3CrMnSi and ha a ma of 1.8 kg. The target i compoed by concrete layer and emi-infinite foundation oil. The target i 5 mm in length and 5 mm in width. And the concrete i 1 mm in thickne. The thickne of foundation oil i taken 2 mm. The trength of concrete material i C2. 3 Numerical imulation With the commercial oftware of LS-DYNA3D, the penetration of flat-noe projectile into target compoed of concrete layer and foundation oil i imulated. 3.1 Calculational Model The calculation wa carried out with the Lagrangian arithmetic. The geometric model i built with quarter part in numerical imulation becaue of ymmetry of the load, the geometry of projectile and target, and boundary condition. The calculational model include the flat-noe projectile, concrete layer and foundation oil. The contact type of eroding_urface_to_urface i adopted between the flat-noe projectile and concrete layer and the contact type of automatic_urface_to_urface i ued between concrete layer and foundation oil. The non-reflection

2 3rd WSAS International Conference on APPLID and THORTICAL MCHANICS, Spain, December 14-16, boundary condition i adopted in the lateral and bottom boundary of the target Foundation oil Concrete Flat-noe projectile 3.2 Model Parameter Becaue of the initial velocity and in order to check the trength propertie of the flat-noe projectile, the kinematic hardening platic contitutive model i ued for the projectile and the elatic brittle model i adopted for concrete. The tenile tre failure criterion are ued for the concrete. The SOIL_AND_FOAM model i ued for the foundation oil [1]. It yield function can be written a [11] 1 f = Sij Sij a + a p+ a p 2 2 ( 1 2 ) Fig.2 Finite element model of projectile and target Fig.2 give a diagram of dicrete finite element model of flat-noe projectile and the combination target. The ize of finite element model are hown in Fig.1. In a particular region, mehe are refined locally to obtain relatively reaonable reult. The entire model include 49,56 element and 57,738 node. Where a, a1, a2 denote the material contant, repectively, p the preure and S ij the deviatoric tree. The relationhip between the preure and the volumetric train i given a 5 p= e 18.9ε The main material parameter are lited in Table 1-Table 3. Here and are denity and elatic modulu, µthe poion ratio, σ b, σ c and σ t the yield trength, the compreive trength and the tenile trength, repectively, BHN the hardening parameter, G and K the hear modulu and the bulk modulu. p v Table 1 Material parameter of 3CrMnSi [12] µ σ b σ c BHN Table 2 Material parameter of concrete (GPa) µ G (GPa) [12, 13] σ b σ t Table 3 Material parameter of oil [13] G K a a 1 a 2 µ

3 3rd WSAS International Conference on APPLID and THORTICAL MCHANICS, Spain, December 14-16, Simulation Reult and Analyi 4.1 Analyi on action of projectile and target Fig.3 how the contour of preure of the projectile and target of different time when the projectile normally penetrate the target with a velocity of 96 m/. From Fig.3, it can be een that penetration depth increae with the time and the zone of tenile damage on the upper urface of concrete expand with the increae of penetration depth. A mall compreive zone i formed in the interface of concrete layer and foundation oil. When tre wave propagate into the oil, the amplitude of preure i mall. From the imulation reult, it how the penetration performance of the flat-noe projectile with the low impact velocity i weak. The penetration characteritic can ue effectively in ome pecial field for the low penetration depth. 4.2 Failure analyi of target Fig.4 preent the damage profile of concrete layer by numerical imulation. It can be een that after the impact of projectile, the cruh zone i formed in the upper and bottom urface of the concrete. The crack zone i adjacent to the cruh zone. Fig.5 how the damage profile of concrete layer in the upper urface of the concrete by experiment under the ame condition with imulation work. Compared with Fig.5, it can be een that the numeric reult i in good agreement with the experimental reult. Thu further tudy can be carried out to obtained more phenomena and concluion by numeric imulation with le cot. (A) t = µ (B) t = 2µ Fig.4 Damage profile of the upper urface concrete layer by imulation (C) t = 1µ (D) t = 4µ Fig.5 xperimental damage profile of Fig.3 Contour of preure a projectile the upper urface in concrete layer penetrating into target

4 3rd WSAS International Conference on APPLID and THORTICAL MCHANICS, Spain, December 14-16, Penetration performance with different initial of projectile By tracking the trajectory of the projectile, the time-diplacement curve, the time-velocity curve and the time-deceleration curve at different impact velocity are obtained a hown in Fig.6, Fig.7 and Fig.8. From Fig.6, it can be een that the penetration depth i le than 2mm when impact velocity change from 77m/ to 96m/ and the penetration depth increae with the impact velocity. Compared with Fig.4, it indicate that the penetration depth of projectile and the penetrating crack and the tenile cruh zone embody the damage of target. d(mm) Fig.6 The curve of penetration depth Fig.7 how the projectile velocity i very mall after 4µ. Compared with Fig.6, the increment of the penetration depth i mall after 4µ for different impact velocity. But when the impact velocity i 77m/, the projectile velocity became negative after 3µ. It indicated that after 3µ the projectile began to rebound and the penetration depth decreae after it reache the maximum. v(m/) t(µ) t/µ v=96m/ v=88m/ v=77m/ v=96m/ v=88m/ v=77m/ Fig.7 The curve of the projectile velocity Fig.8 how the curve of the deceleration with time during penetration proce. It indicate that the greater the velocity of the flat-noe projectile, the greater of the deceleration amplitude. a(1g) Concluion By analyi of the projectile normally penetrating into target through numerical imulation, ome concluion are drawn a follow: (1) Numeric reult how that the hape of the projectile warhead ha a certain effect on the penetration proce. The flat-noe projectile ha a trong impact on the target on the initial time in term of the cutting ring. The impact velocity decreae with the entire contact of the projectile warhead and target and the ultimate penetration capability i not prominent. (2) In the numerical condition of thi paper, the deformation of the projectile i mall which verifie it reliability of trength. When the target i compoed of concrete layer and emi-infinite foundation oil, the impact mainly caue the damage of concrete in the upper layer. The damage zone of the concrete target include the compreive cruh zone in the center of the upper urface and the tenile cruh zone in the center of the bottom urface in the concrete layer and the crack zone adjacent to the cruh zone. (3) The penetration depth increae with the impact velocity. The penetration depth of the projectile and the penetrating crack and the tenile cruh zone embody the damage of the target. The turning point in the beginning tage of the time-penetration depth curve indicate the cutting ring penetrate into target. Reference: t(µ) Fig.8 The curve of the deceleration v=96m/ v=88m/ v=77m/ [1] Luk V K,Forretal M J. Penetration into Semi-infinite Rein-Forced-concrete Target with

5 3rd WSAS International Conference on APPLID and THORTICAL MCHANICS, Spain, December 14-16, Spherical and Ogival Noe Projectile. Int J Impact ngng,1987,6(4) : pp [2] Forretal M J. Penetration of Grout and Concrete Target with Ogive-noe Steel Projectile. Int J Impact ngng,1996,18 (5) : pp [3] Q M Li, X. W Chen. Dimenionle formulae for penetration depth of concrete target impacted by a non-deformable projectile. Int J Impact ngng, 23, 28(1): pp [4] Jan Arild Teland, Henrik Sjøl. Penetration into concrete by truncated projectile. Int J Impact ngng, 24, 3(4): pp [5] Tomonori Ohno, Takahi Uchida, Noriyuki Matumoto, Yohihiko Takahahi. Local Damage of Reinforced Concrete Slab by Impact of Deformable Projectile. Nuclear ngineering and Deign, 1992, 38(1): pp [6] duardo Moreno Almana, Manuel Fernández Cánova. Behaviour of normal and teel fiber-reinforced concrete under impact of mall projectile. Cement and Concrete Reearch, 1999, 29(11): pp [7] C.Y. Tham. Reinforced concrete perforation and penetration imulation uing AUTODYN-3D. Finite lement in Analyi and Deign, 25, 41(14): pp [8] T.L. Teng, Y.A. Chu, F.A. Chang and H.S. Chin. Numerical analyi of oblique impact on reinforced concrete. Cement and Concrete Reearch, 25, 27(4): pp [9] Yuh-Shiou Tai, Chia-Chih Tang. Numerical imulation: The dynamic behavior of reinforced concrete plate under normal impact. Theoretical and Applied Fracture Mechanic, 26, 45(2): pp [1] Hallquit John O. LS-DYNA Theoretical Manual. Livermore Software Technology Corporation, [11] GU Wenbin; Ye Xuhuang; Zhan Fami, etc. Dynamic Analyi on Spherical Charge xploding in Semi-infinite Soil Medium. ngineering Blating, 1999, 5(1) : pp. 5-1 ( in Chinee). [12] Liu Xiaohu; Liu Ji; Wang cheng; Dang Ruirong, xperimental Studie on the Projectile Penetrating Normally into a Plain Concrete, xploion and Shock Wave, 1999,19(4) : pp ( in Chinee). [13] Holmquit T J, Johnon G R, Cook W H. A Computational Contitutive Model for Concrete Subjected to Large Strain, High Strain Rate and High Preure. 14th International Sympoium on Ballitic, 1995, pp